Abstract
<title>Abstract</title> <p>Tomato production in Bangladesh is traditionally confined to the winter season; however, demand and market prices peak during the off-season (March–June), when cultivation is constrained by high temperatures and erratic rainfall. This study evaluated the morpho-physiological adaptation and yield stability of 20 tomato cultivars to identify heat-tolerant cultivars suitable for off-season cultivation under subtropical summer conditions. High ambient temperatures (peaking at 38.2°C) combined with heavy precipitation events (up to 73.4 mm) during the reproductive phase imposed severe physiological bottlenecks, resulting in complete yield failure of late-maturing cultivars. Beer Super produced the highest yield (42.6 t ha⁻¹), attributed to its ability to maintain vegetative vigor, including greater plant height (136.88 cm), higher leaf number (44.92), larger leaf area (195.20 cm²), and lower disease incidence (13.75%) and severity (25.08%). Udayan ranked second (40.4 t ha⁻¹) and exhibited significant earliness, flowering at 27.33 days after transplanting. In contrast, Pusa Rubi, Black Tomato, and Pomodoro failed to set fruit, indicating total reproductive failure under summer stress. Pearson correlation analysis revealed that yield was positively governed by fruit length (r = 0.508, p < 0.01) and negatively influenced by disease incidence (r = − 0.371, p < 0.01). Overall, cultivars exhibiting vigorous vegetative growth, early flowering, and reduced disease pressure maintained superior yield under summer stress. Beer Super and Udayan are therefore identified as promising cultivars for off-season tomato production in Bangladesh, offering farmers an alternative production window and enhancing climate-resilient horticulture.</p>